The present invention relates to an ultrasonic detector insertable into a body cavity that has an ultrasonic probe and a treatment tool projecting port provided at the tip of an insertion portion to be inserted into a body cavity.
As shown in FIG. 6, an ultrasonic detector insertable into a body cavity has a tip forming part 90 provided at the tip of an insertion portion that is to be inserted into a body cavity. The tip forming part 90 has an ultrasonic probe 91 for performing an ultrasonic scan and a treatment tool projecting port 92, through which a treatment tool such as a puncturing needle projects toward an affected area. A cross section of the affected area is imaged by ultrasonic examination. In FIG. 6, a range indicated by the character "A" is the range of ultrasonic scan and the arrow "B" indicates the direction in which a treatment tool is to project.
To examine the liver, the tip of an ultrasonic detector is inserted into the stomach and a short pulse of ultrasonic waves is scanned from the probe into the liver. If it is necessary to obtain a specimen of hepatocyte tissues, a puncturing needle is pierced through the stomach wall into the liver.
For several reasons (for example, the need to provide the puncturing needle with a suitable degree of rigidity, and the practical limitations on the thickness of the insertion portion of the ultrasonic detector), it is difficult to increase the angle at which the puncturing needle projects with respect to the longitudinal axis of the tip forming part 90.
Under the circumstances, if the puncturing needle is to be pierced through the stomach wall into the liver from the illustrated ultrasonic detector, the piercing angle of the needle must be very small with respect to the stomach wall 101 (as shown in FIG. 7) and the needle cannot be pierced into the liver 102 in a precise and positive way.
To solve this problem, it has been proposed, in Unexamined Published Japanese Patent Application (Kokai) No. 143985/1995, that the tip forming part of the insertion portion is shaped to bend in a direction away from the range of ultrasonic scan, thereby ensuring that the angle at which the needle is pierced through the stomach wall is correspondingly increased.
However, if the tip forming part of the insertion portion has such a bent shape, the insertion portion will cause great pain to the patient as it is passed through the esophagus and even more pain will be felt if the insertion portion is oriented in the larynx in the "wrong direction" during removal from a body cavity.